A pneumatic-hydraulic converter is required when a hydraulic caliper brake device, which uses hydraulic oil as a pressure medium, is to be used in a railway vehicle in which air is used as the pressure medium. Accordingly, the general trend is to use a pneumatic caliper brake device to abolish a hydraulic source.
However, in order to use the pneumatic caliper brake device, which generates less force than the hydraulic caliper brake device, in a railway vehicle, a larger actuator becomes necessary. Accordingly, the entire device becomes bulky, and such a bulky device is difficult to install within a limited space.
In this regard, Patent Reference 1 proposes a device in which a smaller pneumatic actuator can be used by utilizing the principle of leverage.
However, in the pneumatic caliper brake device proposed in Patent Reference 1, the dimension of the caliper body is large in its sliding direction as the actuator is arranged coaxially with a sliding portion of the caliper body and one end of a lever is rotatably supported by an end of a rod of the actuator.
Moreover, in the pneumatic caliper brake device proposed in Patent Reference 1, the above problem may be escalated because as the brake shoe gets worn out, the distance of protrusion of the actuator rod during braking may become longer, which may result in requiring a longer stroke of the rod.